[@KatherinWinter]
Well, he's supposed to be one of those aliens that are so technologically superior that they are completely dependent on it. They don't reproduce, they just grow more of themselves in vats, so they're kind of a clone race. Each Zilnaxxian is grown for a couple of weeks in a tube, genetically engineered for a specific purpose. PLX-395 does his job, cause that's what he was grown to do, but it's not like he follows programming or something. He's still got squishy organs, he still needs to eat, he is still a creature, he's just from a technologically superior, totalitarian race of jar babies. As far as his age goes, he may only have been alive for a little over a year, but he was grown as an adult in a matter of weeks. He's been an adult for about a year now, so mentally, he's in his early twenties.